Noise reduction device

Abstract

To improve maintenance workability of a target device.SOLUTION: A noise reduction device 1 comprises: an acoustic duct 2 into which a noise emission part 101 of a target device 100 is inserted; a microphone 3 which detects noise emitted from an exit side of the acoustic duct 2; and a speaker which emits reverse-phase sound having a phase opposite to the noise, from an entrance side of the acoustic duct 2 toward the exit side of the acoustic duct 2. The acoustic duct 2 comprises: a first acoustic duct 10 to which the speaker is attached; a second acoustic duct 20 into which the noise emission part 101 is inserted; and a flexible duct 30 which detachably connects the first acoustic duct 10 and the second acoustic duct 20.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a noise reduction device. [Background technology]

[0002] Patent Document 1 listed below discloses a noise reduction device that reduces noise (exhaust sound) emitted from an exhaust port of a construction machine. This noise reduction device includes a microphone that detects the volume of the noise emitted from a noise outlet, a speaker that emits an anti-phase sound that is in the opposite phase to the phase of the noise, and an acoustic duct to which the speaker is attached and which houses the noise outlet, and uses the anti-phase sound to reduce the noise emitted from the noise outlet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6829055 Summary of the Invention [Problem to be solved by the invention]

[0004] The noise reduction devices of the above-mentioned prior art are installed on the target equipment (construction machinery), so there is room for improvement in terms of the ease of maintenance of the target equipment.

[0005] An object of the present invention is to improve the ease of maintenance of a target device. [Means for solving the problem]

[0006] A noise reduction device according to a first aspect of the present invention comprises an acoustic duct into which a noise emitting portion of a target device is inserted, a microphone for detecting noise emitted from an outlet side of the acoustic duct, and a speaker for emitting an anti-phase sound that is in opposite phase to the noise from the inlet side of the acoustic duct toward the outlet side of the acoustic duct, wherein the acoustic duct comprises a first acoustic duct to which the speaker is attached, a second acoustic duct into which the noise emitting portion is inserted, and a flexible duct that detachably connects the first acoustic duct and the second acoustic duct.

[0007] In addition, according to a second aspect of the present invention, in the noise reduction device of the first aspect, the flexible duct may be fixed to the second acoustic duct and detachable from the first acoustic duct.

[0008] In addition, in a third aspect of the present invention, in the noise reduction device of the first or second aspect, the target device has a moving part that is movable relative to the noise emitting part, the first acoustic duct is fixed to a part of the target device other than the moving part, and the second acoustic duct and the flexible duct are fixed to the moving part via a fixed frame.

[0009] In addition, in a fourth aspect of the present invention, in the noise reduction device of the third aspect, the moving portion may have a plurality of through holes, and the fixed frame may be fixed to the moving portion via the plurality of through holes.

[0010] In addition, in a fifth aspect of the present invention, in the noise reduction device of the third or fourth aspect, the second acoustic duct has an insertion hole into which the noise emitting portion is inserted, and the insertion hole has an insertion hole extension portion that avoids interference between the noise emitting portion and the second acoustic duct when the second acoustic duct moves together with the moving portion, and the second acoustic duct may be provided with a detachable cover that detachably covers the insertion hole extension portion.

[0011] In addition, in a sixth aspect of the present invention, in the noise reduction device of any one of the third to fifth aspects, the connection end of the flexible duct to the first acoustic duct may be connected to the fixed frame via a wire. Effect of the Invention

[0012] According to the above aspect of the present invention, the acoustic duct can be easily installed and separated, and the maintenance workability of the target device can be improved. [Brief description of the drawings]

[0013] [Figure 1] 1 is a side view of a noise reduction device according to an embodiment. [Diagram 2] 1 is a diagram showing an internal configuration of a noise reduction device according to an embodiment; [Diagram 3] FIG. 2 is an installation view of the noise reduction device according to the embodiment, as viewed from the rear. [Figure 4] FIG. 2 is a plan view of a fixing frame according to one embodiment. [Diagram 5] FIG. 2 is a side view of a stationary frame according to one embodiment. [Figure 6] 11A to 11C are diagrams illustrating a procedure for opening an engine cover of a target device according to an embodiment. [Figure 7] 11A to 11C are diagrams illustrating a procedure for opening an engine cover of a target device according to an embodiment. [Figure 8] 11A to 11C are diagrams illustrating a procedure for opening an engine cover of a target device according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] FIG. 1 is a side view of a noise reduction device according to one embodiment. 1, a noise reduction device 1 according to this embodiment is installed in a target device 100, and reduces noise emitted from a noise emitting section 101 of the target device 100. In this embodiment, a construction machine such as an excavator is exemplified as the target device 100. Note that the target device 100 of the noise reduction device 1 is not limited to a construction machine.

[0016] The target device 100 includes a vehicle body 102, an engine room 103 provided at the rear of the vehicle body 102, and an engine cover 104 (movable part) that releasably covers the upper part of the engine room 103. The noise emitting part 101 is an exhaust pipe that protrudes in a substantially vertical position from an engine (not shown) in the engine room 103. The upper end of this exhaust pipe opens toward the rear of the vehicle body 102 and emits noise (exhaust sound).

[0017] In the following description, an XYZ Cartesian coordinate system is set, and the positional relationship of each member may be described with reference to this XYZ Cartesian coordinate system. The X-axis direction is the front-rear direction of the vehicle body 102, the Y-axis direction is the left-right direction of the vehicle body 102, and the Z-axis direction is the height direction of the vehicle body 102.

[0018] The engine cover 104 has an opening (not shown) through which the noise emitting part 101 is disposed, and is rotatable (movable) relative to the vehicle body 102. A rotation shaft 104a of the engine cover 104 is disposed on the rear side (-X side) of the noise emitting part 101 (engine room 103). The engine cover 104 is rotatable rearward about an axis extending in the Y-axis direction with the rotation shaft 104a as its center.

[0019] FIG. 2 is a diagram showing the internal configuration of the noise reduction device 1 according to one embodiment. 2, the noise reduction device 1 includes an acoustic duct 2, a microphone 3, a speaker 4, and an acoustic signal generator 5. One end 2A of the acoustic duct 2 on the inlet side (+X side) is closed, and the other end 2B on the outlet side (-X side) is open. The detailed structure of the acoustic duct 2 will be described later.

[0020] The microphone 3 detects noise emitted from the outlet side (-X side) of the acoustic duct 2. The microphone 3 is provided near the other end 2B of the acoustic duct 2, detects noise (exhaust noise) emitted into the air from the other end 2B, and outputs a noise signal (exhaust noise signal) indicative of the noise to the acoustic signal generator 5. This microphone 3 includes, for example, a diaphragm that vibrates due to sound waves, a voice coil attached to the diaphragm, and a permanent magnet magnetically coupled to the voice coil, and outputs, as the noise signal, an electromotive force generated at both ends of the voice coil in association with the vibration of the diaphragm caused by sound waves.

[0021] The acoustic signal generator 5 generates an acoustic signal (a signal for reducing noise) indicating a sound having an opposite phase to the phase of the noise (opposite phase sound) based on the noise signal. The acoustic signal generator 5 includes, for example, an inverting amplifier circuit that inverts and amplifies the noise signal, and a power amplifier circuit that power-amplifies the output of the inverting amplifier circuit, and outputs the output of the power amplifier circuit as an acoustic signal. In other words, the acoustic signal is a signal having a signal phase obtained by inverting the phase of the noise signal and having an amplitude corresponding to the volume (sound pressure) of the exhaust sound. The acoustic signal generator 5 outputs such an acoustic signal to the speaker 4.

[0022] The speaker 4 emits an anti-phase sound, which is in anti-phase with the noise, from the inlet side (+X side) of the acoustic duct 2 toward the outlet side (-X side) of the acoustic duct 2. The speaker 4 is a sound generator that vibrates a circular diaphragm by driving an electromagnet with the acoustic signal. The speaker 4 is provided within one end 2A of the acoustic duct 2 so that the center of the diaphragm coincides with the central axis of the acoustic duct 2, and emits the anti-phase sound generated by the acoustic signal in the same direction as the emission direction of the noise.

[0023] The acoustic duct 2 includes a first acoustic duct 10 to which the speaker 4 is attached, a second acoustic duct 20 to which the noise emitting part 101 is inserted and to which the microphone 3 is attached, and a flexible duct 30 to detachably connect the first acoustic duct 10 and the second acoustic duct 20. The acoustic duct 2 of this embodiment is formed into a cylindrical shape extending in the X-axis direction as a whole. The acoustic duct 2 may be bent at the flexible duct 30.

[0024] The first acoustic duct 10 is, for example, a cylindrical member, extends in the X-axis direction, and forms one end 2A of the acoustic duct 2. That is, the front side (+X side) of the first acoustic duct 10 is closed with a metal cover or the like. A speaker 4 is attached to an opening on the rear side (-X side) of the first acoustic duct 10 so as to close the opening.

[0025] 1, the first acoustic duct 10 is disposed behind the cabin (driver's seat) of the target device 100, and is fixed to a vehicle body 102 (other than the moving part) via a fixing base 40. An acoustic signal generator 5 is disposed and fixed to the roof of the cabin of the target device 100. The fixing base 40 includes legs 41, a base portion 42, and a support portion 43.

[0026] The legs 41 have a height adjustment mechanism. A plurality of legs 41 are fixed to the lower surface of a base 42 that is rectangular in plan view. At least three legs 41, and preferably four or more legs 41, are provided to ensure support stability. A pair of supports 43 are fixed to the upper surface of the base 42. The pair of supports 43 are disposed to sandwich the first acoustic duct 10 in the Y-axis direction, and are fixed to both sides of the first acoustic duct 10 in the Y-axis direction.

[0027] The pair of support parts 43 are formed with a plurality of fixing holes that enable adjustment of the fixing position of the first acoustic duct 10 in the Z-axis direction. The base part 42 and the vehicle body 102 are fixed by a fixing part (not shown). The fixing part may apply tension between the base part 42 and the vehicle body 102 to restrain the base part 42 to the vehicle body 102, and a plurality of fixing parts may be provided similarly to the legs 41.

[0028] The second acoustic duct 20 is, for example, a cylindrical member, extends in the X-axis direction, and forms the other end 2B of the acoustic duct 2. In other words, the rear side (-X side) of the second acoustic duct 20 is open. An insertion hole 21 into which the noise emitting part 101 is inserted is formed in the lower surface of the second acoustic duct 20. A fixed cover 24 (see FIG. 2) that fits the shape of the engine cover 104 is attached to the opening periphery on the -X side of the insertion hole 21.

[0029] The insertion hole 21 has an insertion hole extension 21a that avoids interference between the noise emitting part 101 and the second acoustic duct 20 when the second acoustic duct 20 rotates (moves) together with the engine cover 104, as described below. The insertion hole extension 21a extends toward the front (+X side), and the insertion hole 21, including the insertion hole extension 21a, is formed in the shape of an elongated hole extending in the X-axis direction in a plan view.

[0030] The second acoustic duct 20 is provided with a removable cover 22 that detachably covers the insertion hole extension 21a. This can reduce noise leakage from the insertion hole extension 21a. The removable cover 22 is formed in an arc plate shape, and both ends in the Y-axis direction are detachably fixed to the circumferential surface of the second acoustic duct 20 by a plurality of fasteners 23. An example of the fasteners 23 is a fastener (a so-called snap lock).

[0031] The flexible duct 30 is a metal bellows tube extending in the X-axis direction, and has flexibility and a certain degree of rigidity. The flexible duct 30 is fixed to the second acoustic duct 20, and is detachable from the first acoustic duct 10. In other words, the flexible duct 30 is fixed to the front end of the second acoustic duct 20 with bolts or the like, and is detachably fixed to the rear end of the first acoustic duct 10 to which the speaker 4 is attached.

[0032] 1, a connection end 31 of the flexible duct 30 to the first acoustic duct 10 is formed in a cylindrical shape and is detachably fixed to the peripheral surface of the first acoustic duct 10 by a plurality of fasteners 32. An example of the fasteners 32 is a fastener (a so-called snap lock). The fasteners 32 are provided at equal intervals in the circumferential direction of the peripheral surface of the connection end 31 (first acoustic duct 10), for example, at three locations.

[0033] The second acoustic duct 20 and the flexible duct 30 configured as described above are fixed to the engine cover 104 via the fixed frame 50. The connection end 31 of the flexible duct 30 is connected to the fixed frame 50 via a wire 60, and its position can be adjusted relative to the first acoustic duct 10 when connected.

[0034] Fig. 3 is an attachment diagram of the noise reduction device 1 according to one embodiment, seen from the rear. Fig. 4 is a plan view of the fixed frame 50 according to one embodiment. Fig. 5 is a side view of the fixed frame 50 according to one embodiment. As shown in FIG. 4, the fixed frame 50 includes a pair of first frames 51A, 51B extending parallel to the X-axis direction.

[0035] As shown in Fig. 3, the first frames 51A and 51B are disposed at different heights according to the shape of the engine cover 104. Specifically, the first frame 51A is disposed lower (on the -Z side) than the first frame 51B. As shown in Fig. 4, the second frames 52A to 52D are erected in the Z-axis direction on the first frame 51A at intervals in the X-axis direction. Similarly, the second frames 52a to 52d are erected in the axial direction on the first frame 51B at intervals in the X-axis direction corresponding to the second frames 52A to 52D.

[0036] A third frame 53 is installed between each of the second frames 52A to 52D and the second frames 52a to 52d. As shown in Fig. 3, the third frame 53 extends in the Y-axis direction n and is disposed below the acoustic duct 2. A fixing piece 62 for fixing the second acoustic duct 20 is attached to the second frames 52A and 52a.

[0037] The fixing pieces 62 are fastened and fixed to the connecting pieces 25 provided on both sides of the second acoustic duct 20 in the Y-axis direction via fastening members such as bolts. The fixing pieces 62 are also attached to the second frames 52B, 52b as shown in Fig. 4. In other words, the second acoustic duct 20 is fixed to the fixed frame 50 at four points.

[0038] A fourth frame 54 extending toward the rear side (-X side) is connected to the second frame 52a. A fixing piece 63 for fixing the microphone 3 is provided on the fourth frame 54. A fifth frame 55 extending toward the outside in the Y axis direction (-Y side) is connected to the first frame 51B. A plurality of fifth frames 55 (two in this embodiment) are provided at intervals in the X axis direction.

[0039] 3, engine cover 104 is provided with a plurality of through holes 104b for the purpose of dissipating engine heat, and fixing frame 50 is fixed to engine cover 104 via the plurality of through holes 104b. Specifically, fixing frame 50 is fixed to engine cover 104 at first frame 51A via restraining device 70 passing through through hole 104b. As restraining device 70, a plastic cable tie can be suitably used.

[0040] Moreover, the fixed frame 50 is fastened to the engine cover 104 by a fixing plate 71 and a fastening member 72 via the through hole 104b at the fifth frame 55. The fifth frame 55 is disposed on the outer side of the engine cover 104. The fixing plate 71 is disposed on the inner side of the engine cover 104. The fixing plate 71 has a plurality of elongated holes formed therein.

[0041] The fastening members 72 include a bolt, a nut, a washer, etc. The head of the bolt is inserted into a dovetail portion (not shown) of the fifth frame 55, and the shaft of the bolt is disposed passing through the through hole 104b of the engine cover 104 and the long hole of the fixing plate 71. The engine cover 104 can be tightened by screwing a nut and a washer onto the shaft of the bolt protruding downward from the fixing plate 71.

[0042] According to the above configuration, even after the noise reduction device 1 is installed, the acoustic duct 2 can be separated and the engine cover 104 can be opened as shown in Figures 6 to 8. Since the engine cover 104 of the target device 100 is frequently opened and closed for daily inspections and the like, it is important in improving the ease of maintenance of the target device 100 that the engine cover 104 can be opened easily as described below. 6 to 8 are diagrams showing a procedure for opening the engine cover 104 of the target device 100 according to one embodiment.

[0043] 6, the fasteners 23 are unlocked and the removable cover 22 is removed from the bottom surface of the second acoustic duct 20. This causes the insertion hole extension 21a of the insertion hole 21 to be exposed. 7, the fastener 32 is unlocked and the connection end 31 of the flexible duct 30 is removed from the first acoustic duct 10. This separates the acoustic duct 2 into front and rear parts. 8, the second acoustic duct 20 and the flexible duct 30 are rotated together with the engine cover 104. During this rotation, the insertion hole extension portion 21a of the insertion hole 21 can prevent interference between the noise emitting portion 101 and the second acoustic duct 20.

[0044] 8 to the state shown in Fig. 1, the above steps are reversed. That is, the second acoustic duct 20 and the flexible duct 30 are rotated together with the engine cover 104 to return them to their original positions, the connection end 31 of the flexible duct 30 is connected to the first acoustic duct 10, and finally the removable cover 22 is attached to the bottom surface of the second acoustic duct 20. Here, since the acoustic duct 2 is provided with a flexible duct 30 that detachably connects the first acoustic duct 10 and the second acoustic duct 20, it is easy to connect to the first acoustic duct 10 by adjusting the position of the flexible duct 30 in the front-to-back, left-to-right, up-down directions, particularly when connecting to the first acoustic duct 10 shown in FIG. 7.

[0045] In this embodiment, the acoustic duct 2 can be easily installed and separated, significantly improving the ease of maintenance of the target device 100. Also, the size of the target device 100 varies depending on the device, but this size difference can be absorbed by the flexibility of the flexible duct 30, widening the range of application of the same device. Furthermore, by bending the flexible duct 30, the flexibility of the layout of the target device 100 of the noise reduction device 1 can be increased.

[0046] As described above, the noise reduction device 1 according to this embodiment includes the acoustic duct 2 into which the noise emitting portion 101 of the target device 100 is inserted, the microphone 3 that detects noise emitted from the outlet side of the acoustic duct 2, and the speaker 4 that emits an anti-phase sound that is in anti-phase with the noise from the inlet side of the acoustic duct 2 toward the outlet side of the acoustic duct 2, and the acoustic duct 2 includes a first acoustic duct 10 to which the speaker 4 is attached, a second acoustic duct 20 into which the noise emitting portion 101 is inserted, and a flexible duct 30 that detachably connects the first acoustic duct 10 and the second acoustic duct 20. This configuration makes it easy to install and separate the acoustic duct 2, improving the maintenance workability of the target device 100.

[0047] In this embodiment, the flexible duct 30 is fixed to the second acoustic duct 20 and is detachable from the first acoustic duct 10. With this configuration, the first acoustic duct 10 can be left on the vehicle body 102 side, and the electrical components on the speaker 4 side do not need to be moved much during maintenance work.

[0048] In this embodiment, the target device 100 has an engine cover 104 that is rotatable relative to the noise emitting part 101, the first acoustic duct 10 is fixed to a portion of the target device 100 other than the engine cover 104, and the second acoustic duct 20 and the flexible duct 30 are fixed to the engine cover 104 via a fixed frame 50. With this configuration, the second acoustic duct 20 and the flexible duct 30 can be rotated together with the engine cover 104.

[0049] In this embodiment, the engine cover 104 has a plurality of through holes 104b, and the fixing frame 50 is fixed to the engine cover 104 via the plurality of through holes 104b. According to this configuration, by utilizing the through holes 104b of the engine cover 104, the fixing frame 50 can be attached and detached without drilling new holes in the engine cover 104.

[0050] In this embodiment, the second acoustic duct 20 has an insertion hole 21 into which the noise emitting portion 101 is inserted, and the insertion hole 21 has an insertion hole extension portion 21a that avoids interference between the noise emitting portion 101 and the second acoustic duct 20 when the second acoustic duct 20 rotates together with the engine cover 104, and the second acoustic duct 20 has a removable cover 22 that detachably covers the insertion hole extension portion 21a. With this configuration, while avoiding interference between the noise emitting portion 101 and the second acoustic duct 20, the removable cover 22 can suppress noise leakage from the insertion hole extension portion 21a in the installed state. If the removable cover 22 were not provided, part of the noise released into the second acoustic duct 20 would leak to the outside through the gap between the noise emitting portion 101 and the second acoustic duct 20 (the insertion hole extension portion 21a). For this reason, in the installed state, it is advisable to attach a removable cover 22 to the insertion hole extension portion 21a to suppress noise leakage from the insertion hole extension portion 21a.

[0051] In this embodiment, the connection end 31 of the flexible duct 30 relative to the first acoustic duct 10 is connected to the fixed frame 50 via the wire 60. With this configuration, the position of the connection end 31 of the flexible duct 30 relative to the first acoustic duct 10 is adjustable, and the connection end 31 does not hang down from the fixed frame 50 even when in the state shown in FIG.

[0052] Although preferred embodiments of the present invention have been described and illustrated above, it should be understood that these are illustrative of the present invention and should not be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the scope of the present invention. Thus, the present invention should not be considered as limited by the foregoing description, but rather by the scope of the claims.

[0053] For example, in the above embodiment, a rotating engine cover is exemplified as the moving part of the target device, but the present invention is not limited to this configuration, and the moving part may be a sliding engine cover. Furthermore, the moving part may be not only an engine cover, but also another cover, a door, a window, etc., that is opened and closed during maintenance of the target device. For example, if the target device is equipped with a battery, an example of another cover is a battery cover that covers the battery. The microphone 3 may also be attached to the second acoustic duct 20 or to the fixed frame 50 . [Explanation of symbols]

[0054] Reference Signs List 1...Noise reduction device, 2...Acoustic duct, 2A...One end, 2B...Other end, 3...Microphone, 4...Speaker, 5...Acoustic signal generator, 10...First acoustic duct, 20...Second acoustic duct, 21...Insertion hole, 21a...Insertion hole extension, 22...Detachable cover, 23...Metal fitting, 24...Fixed cover, 25...Connecting piece, 30...Flexible duct, 31...Connection end, 32...Metal fitting, 40...Fixed base, 41...Legs, 42...Base, 43...Support, 50...Fixed frame, 51A ...first frame, 51B...first frame, 52a to 52d...second frame, 52A to 52D...second frame, 53...third frame, 54...fourth frame, 55...fifth frame, 60...wire, 62...fixing piece, 63...fixing piece, 70...restraint, 71...fixing plate, 72...fastening member, 100...target device, 101...noise emitting part, 102...vehicle body, 103...engine room, 104...engine cover, 104a...rotating shaft, 104b...through hole

Claims

1. an acoustic duct into which a noise emitting portion of the target device is inserted; A microphone for detecting noise emitted from the outlet side of the acoustic duct; a speaker that emits an antiphase sound that is in antiphase with the noise from the inlet side of the acoustic duct toward the outlet side of the acoustic duct, The acoustic duct comprises: a first acoustic duct to which the speaker is attached; a second acoustic duct into which the noise emission portion is inserted; and a flexible duct that detachably connects the first acoustic duct and the second acoustic duct. Noise reduction device.

2. the flexible duct is fixed to the second acoustic duct and is detachable from the first acoustic duct.

2. The noise reduction device of claim 1.

3. the target device has a moving part that is movable relative to the noise emitting part, The first acoustic duct is fixed to a portion of the target device other than the moving portion, The second acoustic duct and the flexible duct are fixed to the moving part via a fixed frame.

3. A noise reduction device according to claim 1 or 2.

4. The moving portion has a plurality of through holes, The fixed frame is fixed to the moving part via the plurality of through holes.

4. The noise reduction device according to claim 3.

5. the second acoustic duct has an insertion hole into which the noise emitting portion is inserted, the insertion hole has an insertion hole extension portion that avoids interference between the noise emission portion and the second acoustic duct when the second acoustic duct moves together with the moving portion, The second acoustic duct includes a removable cover that detachably covers the insertion hole extension portion.

4. The noise reduction device according to claim 3.

6. The connection end of the flexible duct to the first acoustic duct is connected to the fixed frame via a wire.

4. The noise reduction device according to claim 3.

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